Need some help with these Kinematics problems, I'll make sure to leave a good review

1. If the average velocity of an object is zero in some time interval, what can you say about the displacement of the object during that interval?

2. A person walks first at a constant speed of 5.00 m/s along a straight line from point A to point B and then back along the line from B to A at a constant speed of 3.00 m/s. (a) What is her average speed along the entire trip? (b) What is her average velocity over the entire trip?

3. A 50 g ball traveling at a velocity of 25.0 m/s bounces off a wall and rebounds at 22.0 m/s. A high speed camera records this event. If the ball is in contact with the wall for 3.50 milliseconds, what is the magnitude of the average acceleration of the ball during this time interval? (Reminder, 103 milliseconds = 1 second)

4. An object moving with uniform acceleration has a velocity of 12.0 cm/s in the positive x direction when its x coordinate is 3.00 cm. If its x coordinate 2.00 s later is -5.00 cm, what is its acceleration?

5. The driver of a car slams on the brakes when he sees a tree blocking the road. The car slows uniformly with an acceleration of -5.00 m/s2 for 4.20 s, making straight skid marks 62.4 m long, ending at the tree. With what speed does the car then strike the tree?

6. A baseball is hit so that it travels straight upward after being struck by the bat. A fan observes that it takes 3.00 s for the ball to reach its maximum height. Find: a) The ball's initial velocity and b) the height it reaches.

7. A ball is thrown directly downward with an initial speed of 8.0 m/s, from a height of 30.0 m. After what time interval does it strike the ground?